This invention relates to an electrically non-conductive operating rod assembly for a bolted-pressure contact switch and particularly to an operating rod assembly which utilizes a threaded metal rod and insulator links of molded high-strength dielectric material.
Fused load-break switches are frequently used as service entrance equipment and in other relatively high current applications. Typically, multiple-pole switches of this kind may be required to interrupt currents of 400-20,000 amperes. These switches are rated for 208,240,480 or 600 volt service. While 600 volt service is not common, a switch rated for this service provides a greater safety margin when used in lower voltage installations.
Most switches of the load-break type are provided with positive pressure applying mechanisms for assuring good contact between the switch terminals. The contacts of these switches are opened and closed rapidly to minimize arcing and thereby avoid pitting and deterioration of the switch contacts. Rapid opening and closing of the switch contacts have been accomplished by the use of an overcenter spring drive. The spring drive can be energized and the switch actuated by manual or electrical means. The manual or electrical means is not used directly to open or close the switch contacts but, instead, operates a trip mechanism to release the spring drive. The overcenter spring drive and its actuating means is commonly referred to as the switch operator mechanism.
The switch operator mechanism is located away from the switch contacts so as to be out of the arcing zone of the contacts. The switch operator mechanism is connected to the contacts by an operating rod assembly and a crossbar. The crossbar, which is made of an insulating material, is connected to the movable contacts. The operating rod assembly is connected to a bracket affixed to the crossbar. In the past, the operating rod has been of a fixed length and formed from laminated strips of phenolic impregnated cloth. Operating rods of this previous construction have presented problems in manufacturing and assembling and did not provide any flexibility of adjustment to compensate for misalignment of the parts of the switch.